Light-sensitive copying composition containing a light insensitive polymer and a light sensitive heterocyclic compound

ABSTRACT

The invention relates to a light-sensitive copying composition comprising a high molecular weight light-insensitive polymer and a light-sensitive nitrogen compound containing at least one sixmembered N-heterocyclic nucleus and at least one benzene nucleus.

1: et a].

Sikora; Hans Werner Frass, both of Wiesbaden-Biebrich, all of Germany Kalle Aktiengesellseliaft, Wiesbaden-Biebrich, Germany Filed: Dec. 28, 1971 Appl. No.: 213,154

Assignee:

US. Cl. 96/115 R, 96/88 Int. Cl G031: 1/68 Field of Search 96/90, 89, 88, 115 R, 96/35, 36

[ Dec. 4, 1973 [56] References Cited UNITED STATES PATENTS 2,980,535 4/1961 Schroeter et a]. 96/35 3,617,278 11/1971 Holstead et a1.... 96/90 3,667,954 6/1972 ltano et a] 96/89 3,519,424 7/1970 Reynolds et a]. 96/1 15 X Primary Examiner--Norman G Torchin Assistant ExaminerWon I-l. Louie, Jr. Att0rneyJames E. Bryan [5 7] ABSTRACT The invention relatesto a light-sensitive copying composition comprising a high molecular weight lightinsensitive polymer and a light-sensitive nitrogen compound containing at least one six-membered N- heterocyclic nucleus and at least one benzene nucleus.

4 Claims, No Drawings LIGHT-SENSITIVE COPYING COMPOSITION CONTAINING A LIGHT INSENSITIVE POLYMER AND A LIGHT SENSITIVE I-IETEROCYCLIC COMPOUND This invention relates to a light-sensitive copying composition which is positive-working, i.e. whose solubility increases by exposure to light.

Positive-working copying compositions and copying materials based on o-quinone diazides are used on a large scale in the reproduction field. During lightdecomposition, these compounds are converted into five-ringed carboxylic acids which are more readily soluble in aqueous alkalies than are the undecomposed compounds. It is possible to incorporate in these copying layers compounds of relatively high molecular weight, in particular condensation resins, in order to improve their copying and printing characteristics, but these additives have not been known to take part in the photoreaction. The compounds have the disadvantage of being thermolabile and not very light-sensitive.

Other known positive-working systems consist essentially of hexaaryldiimidazolyles and condensation resins. However, copying materials prepared from such compounds yield printing plates of low efficiency.

The present invention provides a novel, positiveworking light-sensitive copying composition of high light-sensitivity and good shelf life, which yields copies of high mechanical strength after development.

The subject of the present invention is a lightsensitive copying composition which contains, as the essential constituents, a high molecular weight substance which is insensitive to light, and a light-sensitive nitrogen compound, and in which the high molecular weight substance is a polymer and the light-sensitive nitrogen compound contains at least one six-membered N-heterocyclic nucleus and at least one benzene nucleus, either as a substituent or in annelated form, further non-light-sensitive substituents being attached to these nuclei, if desired.

Pyridine, pyrazine, or dihydropyrazine rings are preferred as heterocyclic nuclei. Acridine, phenazine, and 2,3-diphenyl-quinoxaline are preferred as fundamental substances of the heterocyclic nitrogen compounds to be used according to the invention. Most advantageously, these fundamental substances carry substituents or annelated benzene rings. Suitable substituents are, e.g., alkyl, alkoxy, nitro, dimethylamino, acetylamino, or phenoxy groups, and halogen atoms.

Alkoxy groups, and in particular methoxy groups, are preferred as substituents. The following compounds may be used with advantage, e.g.:

9-phenyl-acridine,

9-p-methoxyphenyl-acridine,

9-p-hydroxyphenyl-acridine,

9-acetylamino-acridine,

benz(a)-acridine lO-methyl-benz(a)-acridine,

benz-(a)-phenazine,

9, l O-dimethyl-benz( a)-phen azine,

9-methyl-benz(a )-phenazine/ l -methyl-benz(a)- phenazine,

9-methoxy-benz(a)-phenazine/l0-methoxy-benz(a)- phenazine,

dibenz(a,c)-phenazine,

l l-methoxy-dibenz(a,c)-phenazine dibenz(a,j )-phenazine,

2 dibenz(f,h)-pyrido(2,3-b)-quinoxaline,

6, 4, 4"-trimethoxy-2,3-diphenyl-quinoxaline,

6-methoxy-2,3-diphenyl-quinoxaline,

4-(4-methoxy-phenyl)-2-phenyl-quinoxaline, 6-chloro-4', 4"-dimethoxy-2,3-diphenylquinoxaline,

6,7-dimethyl-4, quinoxaline,

2,3-di-pyridyl-(2)-5-aza-quinoxaline, 2,3-bis-(4-methoxy-phenyl)-5,6-dihydropyrazine, 2,5-bis-(2,4-dimethoxy-phenyl)-pyrazine, 2,3,5,6-tetrakis-(4-methoxy-phenyl)-pyrazine, 2,3-diphenyl-5,6-dihydropyrazine.

In copending application Ser. No. 149,390, and copending application Ser. No. 170,311, many of these compounds have already been proposed as photoinitiators for photopolymerizable copying compositions. The effect described in these patent applications is that they incite the photopolymerization of certain monomers, the exposed areas of the layers being hardened. In contradistinction thereto, the copying compositions according to the present invention become more easily soluble in the exposed areas. So far, nothing is known about the mechanism is the reaction which takes place during exposure.

Among the heterocyclic compounds to be used according to the invention, the acridines substituted in the 9-position, in particular Q-phenyl-acridine, and further 4, 4"-dimethoxy-2,3-diphenyl-quinoxaline and its derivative substituted in the 6-position, especially the 6-methoxy-derivative, are preferred.

For commercial purposes, the copying composition according to the invention may be used in the form of a solution or dispersion, e.g. as a so-called photoresist composition, which is applied by the consumer to an individual support, e.g. for chemical milling, for the production of printed circuits or stencils, or for making name plates, screen printing stencils and the like, and

4' -dimethoxy -2,3-diphenylwhich is exposed after drying and then developed to form an image-wise differentiated layer.

In particular, the copying composition according to the invention may be marketed in the form of a solid photopolymerizable layer on a support, i.e. as a lightsensitive reproduction material from which printing forms, relief images, etch resists, stencils, mats, screen printing stencils, color proofing films, single copies, and the like may be produced. An important application is their use for the production of storable, presensitized printing plates for planographic, relief, and intaglio printing.

The copying compositions according to the invention are characterized by a high light-sensitivity and excellent thermal stability. As compared with diazo compounds, they have the further advantage that no gaseous nitrogen is produced in the reproduction layer during exposure. As a further advantage, they enable the production of positive relief images or relief printing plates.

Further, the copying compositions according to the invention contain a high molecular weight polymer which preferably contains units carrying acid substituents, especially carboxylic acid, phosphonic acid, sulfonic acid, or N-arylsulfonyl-urethane groups, in combination with other units. Copolymers of acrylic and methacrylic acid esters are suitable.

The polymers form the main constituent of the copying composition (calculated on its solids content). As

a rule, the light-sensitive substance is added in a proportion ranging from 0.5 to 30, preferably from 5 to 15, parts by weight per 100 parts by weight of the polymer.

Additionally, dyestuffs. pigments, plasticizers, wetting agents, and color precursors may be added to the copying compositions. Advantageously, these additives should be selected so that they do not absorb the light required for the photo reaction.

If triphenyl methane dyes or phenazine dyestuffs are added to the layers, the dyestuffs are bleached out in the areas struck by light, so that directly visible images are produced.

Suitable plasticizers and wetting agents, are, e.g.: triethylene-glycol, dibutyl-phthalate, polyoxyethylenesorbitan-fatty acid esters, polyoxyethylene ethyl ether, p-nonylphenol-polyglycol ether, and Polywachse (available from Chemische Werke Huls A. G., Marl, Germany). By means of these additives, the flexibility of the layer may be adjusted and its developing speed controlled.

When the copying compositions are to be applied to copper supports, organic sulfur compounds, such as 2-mercapto-benzthiazole, may be added to improve their adhesion.

The copying compositions according to the invention are preferably used for the production of relief printing forms, relief images, off-set printing forms, bimetal or trimetal printing forms, printed circuits, screen printing stencils, and screen-less offset printing forms.

When the copying composition is to be stored in liquid form, as a so-called photoresist composition, which is to be applied to the support, e.g. a screen printing support, a conductive plate or the like, only immediately before use, the constituents of the layer are dissolved or dispersed in a suitable solvent or solvent mixture. Suitable solvents are, e.g., alcohols, ketones, esters, ethers, amides, hydrocarbons, and the like. The partial ethers of polyhydric alcohols, especially of glycols, are preferred.

if printing plates and the like are to be produced, it is of advantage to apply the solutions or dispersions immediately after their preparation to a suitable support, and to store and market the resulting products as lightsensitive reproduction materials. For this purpose, the same or similar solvents may be used as for the preparation of the photoresist compositions. The solutions or dispersions are applied by casting, spraying, or immerslon.

Suitable supports are, e.g., zinc, copper, aluminum, or steel plates, polyester or acetate films, Perlon gauze, and the like, the surfaces being subjected to a pretreatment, where necessary.

If necessary, an adhesion-improving intermediate layer or an anti-halo layer may be provided between the support and the light-sensitive layer.

After the customary exposure process, the copying layers are advantageously developed by means of organic solvents, e.g. acetone, methyl ethyl ketone, ethyleneglycol monoethyl ether, trichloroethylene, or glycerol, to which water or acids, e.g. sulfuric acid, may be added if desired.

When the developed copying material is to be used as a printing form, the layer may be burned-in by heating it to an elevated temperature, e.g. above 180 C, in order to improve its resistance to abrasion and thus increase the length of the runs obtainable.

In the following examples, different embodiments of the invention are described. Percentages and proportions are by weight unless stated otherwise. One part by weight corresponds to 1 g, when the part by volume is 1 ml.

EXAMPLE 1 A coating solution is prepared from 2.5 parts by weight of a methylmethacrylate/methacrylic acid copolymer having an average molecular weight of about 32,000 and an acid number of 137,

0.01 part by weight of Supranol Blue GL (C.l.

20.0 parts by weight of ethyleneglycol monomethylether, and

9-phenyl acridine in increasing quantities, and whirl-coated upon electrolytically roughened and anodized aluminum of 0.3 mm thickness and dried by heating it for 2 minutes to 100 C.

Using a Kodak gray wedge whose steps differ by an exposure factor of 1.4, the samples are exposed for 2 minutes to a tubular exposure lamp marketed by Messrs. Moll, of Solingen-Wald, Germany, and equipped with 13 fluorescent tubes of the type Philips TL-Ak-4O W/OS" arranged on a X 60 cm area.

The exposed samples are developed by treating them for 30 seconds with ethyleneglycol monoethyl ether containing about 10 per cent of water and 10 per cent of concentrated sulfuric acid, and then inked with protective ink.

The results are as follows:

The light-sensitivity increases with increasing initiator content. In the following Table l, the number of fully exposed, i.e. completely removed steps of the step wedge is stated, and additionally, in brackets, the number of intermediate steps, at different contents of 9- phenyl-acridine:

TABLE 1 Parts b.w. of 9-Phenyl-Acridine Number of Steps 0.15 0 (1) 0.20 0.30 4-5 (1-2) 0.45 5 (2) 0.60 6 0.75 9-10 (4) EXAMPLE 2 A coating solution is prepared from 2.5 parts by weight of the polymer described in Example 1,

0.2 part by weight of 9-phenyl-acridine,

0.01 part by weight of Supranol Blue GL, and

20.0 parts by weight of ethyleneglycol monoethyl ether, and whirl-coated upon an electrolytically roughened anodized aluminum plate the oxide layer of which corresponds to a weight of 3 g per square meter. The coated layer is dried for 2 minutes at C to a weight of 5 g per square meter.

The material is then exposed under a positive photographic original as described in Example 1, developed by immersing it for 15 seconds in acetone to remove the non-image areas, and finally wiped over with an aqueous solution of sodium metasilicate. The plate is then rinsed with water, fixed by means of 1 per cent phosphoric acid, inked with protective ink, and coated with an aqueous solution of gum arabic for preservation, if desired.

The offset printing from thus produced yields at least 100,000 flawlessprints when used for printing in an off set printing machine (type Dualith manufactured by Messrs. Davidson, USA).

For improving its resistance to abrasion, the offset printing form may be burned-in for minutes at a temperature of 240 C. In this case, the printing run is increased to at least 200,000 copies.

EXAMPLE 3 TABLE II Light-Sensitive Compound 6-chloro-4',4-dimethoxy-2,3-

diphenyl-quinoxaline Number of Steps 6 (2) 9-phenyl-acridine S (2) benz(a)*acridine 5 (2) benz(a)-phenazine 2 (2) 6,4',4"-trimethoxy-2,3- 2 (2) diphenyl-quinoxaline o-acetylamino-4,4"-dimcthoxy- 0 (3) 2,3-diphcnyl-quinoxaline mixture of esters of napthoquinone- 0 (0) 1,2-diazide-(2)-5-sulfonic acid and 2,3,4-trihydroxybenzophenone The known positive-working diazo compound, which is used, as a comparison test, in the quantitystated above, yields no image, even after a considerably longer time of exposure.

EXAMPLE 4 A coating solution is prepared from 2.5 parts by weight of a methylacrylate/methacrylic acid copolymer having an average molecular weight of about 30,000 and an acid number of 157,

which after-diffusion of oxygen during exposure is impeded by the top layer, is found to be higher by 180%.

This effect is also observed when using other nitrogen-containing heterocyclic compounds as lightsensitive substances.

EXAMPLE 5 A coating solution is preparedfrom 2.5 parts by weight of a copolymer of methlmethacrylate and N-(p-toluene-sulfonyl)-carbamic acid- (B-methacryloxy)-e thylester (65: 35, acid number t 0.4 part by weight of 9-phenyl-acridine,

0.004 part by weight of Ethyl Violet (C.l. Basic Violet 4), and

20.0 parts by weight of ethyleneglycol monoethyl ether, and whirl-coated upon a 0.3 mm thick plate of anodized aluminum.

The plate is dried and then exposed for 4 minutes under a positive original, which may be a Kodak gray wedge, to the light of a xenon point lamp of 5,000 watts marketed by Messrs. Staub of Neu-lsenburg, Germany, under the designation COP XP 5,000. The plate is then developed by a 10 minutes treatment with the devel oper used in Example 1.

The quality of the image produced corresponds to that of the images obtained according to Example 3.

EXAMPLE 6 A coating solution is prepared as described in Example 2', but without adding a dyestuff, and whirl-coated upon a 125 p. thick, biaxially stretched polyester film provided with a hydrophilic adhesion-improving intermediate layer according to DAS (German published patent application) No. 1,228,414 and then dried. Exposure and development are as described in Example 1 The copy obtained may be clamped in an offset copier (Model 321 of A. B. Dick Company, Chicago,

111., U. S. A.) and used for making copies.

EXAMPLE 7 A coating solution is prepared from 2.5 parts by weight of methylmethacrylate/acrylic acid copolymer having an average molecular weight of 60,000 and an acid number of 82,

0.25 part by weight of polyoxyethylene-sorbitanmonolaurate (TWEEN 20, a product of Atlas Chemical Industries, Inc., Wilmington, Delaware, U. S. A.

0.4 part by weight of 9-phenyl-acridine,

0.01 part by weight of the phenazine dyestuff used in Example 1, and

20.0 parts by weight of ethyleneglycol monoethyl ether,

and whirl-coated upon anodized aluminum and dried. The plate is exposed for 2 minutes under a positive original (e.g. a Kodak gray wedge as used in Example 1) and developed by immersing it for 30 seconds in trichloroethylene. After fixing it with 1 per cent phosphoric acid and inking with greasy ink, the plate is ready for printing.

EXAMPLE 8 A coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

0.2 part by weight of 9-phenyl-acridine,

0.75 part by weight of polyoxyethylenesorbitanmonolaurate (TWEEN 20), and

5.0 parts by weight of ethyleneglycol monoethyl ether, and cast upon an aluminum sheet of 0.3 mm thickness. Most of the solvent is allowed to evaporate at room temperature, and then the plate is dried for 3 hours at C.

For the preparation of a relief image or a relief printing form, the reproduction layer is exposed for 20 minutes under a positive photographic original, using the tubular exposure device described in Examplel, and then developed by brushing it for 5 minutes with the developer mentioned in Example 1.

The thickness of the copying layer is 0,43 mm, and it is washed-out to a depth of 0.185 mm.

The polyethylene-sorbitan-monolaurate used above may be replaced by polyoxyethylene cetyl ether, or pnonyl-phenol-polyglycol ether, or by triethyleneglycol, relief images of comparable quality being produced.

EXAMPLE 9 A coating solution prepared as described in Example 2 is mixed with 0.1 part by weight of 2-mercaptobenzthiazole, and the resulting mixture is whirl-coated upon the cleaned copper surface of a copper-aluminum bimetal plate and then dried for 2 minutes at 100 C.

The plate is exposed for 2 minutes under a positive original, e.g. a Kodak gray wedge of the type described in Example 1, and then developed for 40 seconds with the developer used in Example 1.

For the preparation of a bimetal offset printing plate, the bared copper areas are etched away within 1 minute by means of an iron-trichloride etching solution (400 Series" ALC Etch, type LS 402, marketed by the Fred K.H. Levey Company lnc., New York, N. Y., U. S. A.), whereupon the plate is wiped over with a 1 per cent phosphonic acid solution and inked with greasy ink.

EXAMPLE 10 For the preparation of color proofing films, four coating solutions corresponding to that used in Example 2 are prepared, but instead of adding the dyestuff used in Example 2, the solutions are colored as follows:

a. Yellow Film: 0.07 part by weight of Fat Yellow b. Red Film: 0.08 part by weight of Zapon Fast Fiery Red B (C.l. Solvent Red 109) c. Blue Film: 0.01 part by weight of Ethyl Violet (C.l. Basic Violet 4), and

d. Black Film: 0.80 part by weight of Fat Black HB (C.l. 26,150)

Each of these solutions is whirl-coated upon a 37 ,u. thick, biaxially stretched polyethylene terephthalate film and tried as described in Example 2. The layers thus produced are then exposed under the appropriate silver film color separations (3minutes for the blue and red films, and 5 minutes for the yellow and black films), using a tubular exposure device, and each is developed for seconds with the developer used in Example 1.

By superimposing the color separations produced, a copy is obtained which corresponds to the original of the silver film separations.

Example 1 1 A coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

0.2 part by weight of benz(a)-acridine, 0.01 part by weight of Zapon Fast Fiery Red B (C.I.

Solvent Red 109), and 20.0 parts by weight of ethyleneglycol monoethyl ether, and whirl-coated upon a trimetal plate consisting of layers of aluminum, copper, and chromium, and dried. The plate is exposed as described in Example 1 under a negative original and developed for seconds with the developer used in the same example.

The bared chromium areas are etched away within 7 minutes by means of an etching solution consisting of 17.4% of CaCl 35.3% of ZnC1 2.1% of HCl, and 45.2% of water, and the photoresist layer is then removed with alcohol. Finally, the plate is wiped over with a 1% phosphoric acid solution and inked with greasy ink. The trimetal plate is now ready for printing.

EXAMPLE 12 For the preparation of a zinc relief printing form, a coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

0.2 part by weight of 4"-dimethoxy-2,B-diphenyl-quinoxaline,

0.02 part by weight of Ethyl Violet (C.l. Basic Violet 4), and 20.0 parts by weight of ethyleneglycol monoethyl ether, and whirl-coated upon a cleaned zinc plate suitable for powderless etching and then dried.

The plate is exposed for 3 minutes under the tubular exposure device described in Example 1 and developed by treating it for 1 minute with the developer used in Example 1.

The bared zinc surface is then etched for 6 minutes at room temperature with a 6% solution of nitric acid. The printing form thus produced is suitable for high quality letterpress printing.

EXAMPLE 13 A coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

02 part by weight a of 4'-tert. -butyl-9-phenylacridine,

0.02 part by weight of the dyestuff used in Ex. 12,

and

20.0 parts by weight of ethyleneglycol monoethyl ether, and whirl-coated upon a mechanically roughened aluminum foil of 0.3 mm thickness and dried.

Exposure and development are as described in Example 1. The quality of the printing plate thus produced corresponds to that of the plate described in Example 2.

EXAMPLE 14 A coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

0.2 part by weight of 6-chloro-4,4"-dimethoxy-2,3-

diphenyl-quinoxaline, 0.25 part by weight of the wetting agent used in Ex.

0.02 part by weight of Ethyl Violet (C.l. Basic Violet 4) and 15.0 parts by weight of ethyleneglycol monoethyl ether, applied to a mono-filament Perlon fabric having threads per cm, and dried.

The material is exposed for 5 minutes under a negative original, using the tubular exposure device described in Example 1, and then developed for 2 minutes by means of the developer used in Example 1.

The stencil thus produced may be used for screen printing.

EXAMPLE 15 A coating solution is prepared as described in Example 14 and applied to the cleaned copper surface of a support consisting of a plate of plastic material with a copper skin laminated thereto. After drying, the coating weighs g per square meter.

The material is exposed for 10 minutes under a positive original, using-a tubular exposure device corresponding to that described in Example 1, then developed for 30 seconds with the developer used in Example l, and finally etched for 20 minutes with an irontrichloride solution of 42Be.

The reproduction layer used in this Example is distinguished by its excellent resistance to etching and good resolution capacity.

EXAMPLE 16 A coating solution is prepared from 2.5 parts by weight of a methylmethacrylate/methacrylic acid copolymer having an average molecular weight of about 20.000 and an acid number of 95,

0.01 part by weight of Rhodamine B,

0.2 part by weight of 2,3-bis-(4-methoxy-phenyl)- 5,6-dihydropyrazine, and

20.0 parts by weight of ethyleneglycol monoethylether, whirl-coated, at 100 revolutions of the plate whirler per minute, upon an electrochemically pretreated aluminum plate of 0.1 mm thickness, and dried for 2 minutes at 100 C.

The resulting plate is exposed for 2 minutes from a distance of 72 cm under a positive original, using an 8,000 watt xenon lamp. For development, the plate is wiped over for 35 seconds with the developer used in Example 1.

After fixing with l per cent phosphoric acid, the plate is inked up with greasy ink. The quality of the printing plate thus produced is similar to that of the plate described in Example 3.

EXAMPLE 17' A coating solution is prepared from 2.5 parts by weight of the polymer described in Ex.

0.15 part by weight of 2,5-bis-(2',

4'-dimethoxy-phenyl)-pyrazine, 001 part by weight of Rhodamine B,

0.2 part by weight of the wetting agent used in Ex. 7,

and

20.0 parts by weight of cyclohexanone, and whirl-coated, at revolutions per minute, upon an electrochemically pretreated aluminum plate of a thickness of 0.1 mm. The plate is dried and then exposed for 2 minutes, from a distance of 72 cm, under a positive original, using an 8,000 watt xenon lamp.

The exposed plate is developed by wiping it for 45 seconds with the developer described in Example 1, then treated wth a 1 per cent phosphoric acid solution, and inked up with protective ink.

The quality of the resulting printing plate corresponds to that of the plate described in Example 16.

lt will be obvious to those skilld in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

l. A light-sensitive copying composition comprising a high molecular weight light-insensitive polymer containing units having carboxylic groups, phosphonic acid groups, sulfonic acid groups, or N-arylsulfonyl urethane groups,

and a light-sensitive compound comprising at least one heterocyclic nucleus selected from the group consisting of pyridine, pyrazine, and dihydropyrazine rings, and at least one benzene ring in the form of a substituent or fused to said heterocyclic nucleus, said light-sensitive compound being either unsubstituted or substituted by one or more substituents selected from the group consisting of alkyl, alkoxy, nitro, dimethylamino, acetylamino, and phenoxy groups, and halogen atoms.

2. A copying composition according to claim 1, in which the light-sensitive nitrogen compound is an acridine, or a 2,3-diphenyl quinoxaline substituted by methoxy groups, or a phenazine.

3. A copying composition according to claim 1, in the form of a solid light-sensitive layer upon a support.

4. A copying composition according to claim 3, in which the layer has a top layer of low oxygen permeability on its exposed surface.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,776,735 Dated December 4, 1973 Inventor(s) Sigrid Bauer et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

i The following should be inserted after item on the cover page:

' Foreign Application Priority Data December 30, 1970 Germany. .7 P 20 64 380.5-

Column 2, line 24, "is" should read of Column 7,11r1e 1, "0,43" should read 0.43

Column 7, line'38, "0.80" should read 0.08

Signed and seeled this 7th day of May 197 (SEAL) Attest:

EDWARD l-l.l LETCiH3R,.J1-i. C. MARSHALL DAMN Attesting Officer Commissioner of Patents FORM PO-10 (10-69) USCOMM-DC scan-Pea 1* 0.5. GOVERNMENT PRINTING OFFICE Ill O-BGi-Sfil 

2. A copying composition according to claim 1, in which the light-sensitive nitrogen compound is an acridine, or a 2,3-diphenyl quinoxaline substituted by methoxy groups, or a phenazine.
 3. A copying composition according to claim 1, in the form of a solid light-sensitive layer upon a support.
 4. A copying composition according to claim 3, in which the layer has a top layer of low oxygen permeability on its exposed surface. 